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Spatial distribution of phase singularities in ventricular fibrillation.

BACKGROUND: Multiple excitation wavelets are present during ventricular fibrillation (VF). The underlying wavelet organization of VF is unclear. Phase singularities (PSs)-locations of ambiguous activation state-underlie reentry and wavelet splitting and represent the sources of VF. Understanding the mechanisms of PS formation might be important in the development of effective therapies for sudden death. METHODS AND RESULTS: We performed voltage, phase, and PS mapping in fibrillating ventricles, applying an automated PS detection algorithm to optically recorded fibrillation signals. PS clustering was noted along epicardial vessels, ridges of endocardial trabeculae, and papillary muscle insertions. Microscopically, these locations correlated with areas of apposition of fibers with different angulations and intramural vessels. A total of 83.2% of PSs were formed at and meandered about these anatomic structures, which acted as stabilizers: PSs colocalizing at anatomic substrates had longer life spans than nonanatomic PS (82.46+/-60.8 versus 40.5+/-31.9 ms, P<0.01). The RV endocardium had a higher PS incidence than the epicardium (42.3+/-9.2 versus 23.5+/-11.6 PS/s, P<0.01). Autocorrelation showed that irregular behavior was spatially restricted to anatomic heterogeneities compared with other areas, which had nearly periodic behaviors. Simple spatial PS distributions underlay complex and variable activation patterns attributable to variable PS behaviors, life spans, and inter-PS interactions. CONCLUSIONS: PSs occur in a nonrandom spatial distribution and colocalize with normal anatomic heterogeneities. Varying PS behaviors and life spans but stable PS spatial distributions cause ever-changing activation patterns that characterize VF.

Animals↗

Memory-specific temporal profiles of gene expression in the hippocampus.

Many experiments in the past have demonstrated the requirement of de novo gene expression during the long-term retention of learning and memory. Although previous studies implicated individual genes or genetic pathways in learning and memory, they did not uncover the collective behaviors or patterns of the genes. We have used genome-scale screening to analyze gene expression during spatial learning of rats in the Morris water maze. Our results show distinct temporal gene expression profiles associated with learning and memory. Exogenous administration of one peptide whose sustained increase during memory retention was implicated by microarray analysis, fibroblast growth factor (FGF)-18, improved spatial learning behavior, suggesting that pharmacological modulation of pathways and targets identified may allow new therapeutic approaches for improving learning and memory. Results of this study also suggest that while learning and physical activity involve common groups of genes, the behavior of learning and memory emerges from unique patterns of gene expression across time.

Animals↗

Spatial memory and choice behavior in the radial arm maze after fornix transection.

In the radial arm maze task, it is well established that performance of rats with hippocampal damage is severely impaired on the place version, which relies heavily, if not exclusively, on spatial information. However, very little is known about the effects of hippocampal damage on actual choice behavior. To address this issue, sham-operated (SH) and fornix-transected (FX) rats were trained and tested on the place task in the eight-arm radial maze. The following measures were recorded: the frequency of re-entry errors, the number of choices separating repeated visits to the same arm, the latency to arm re-entry, the distribution and targets of microchoices defined as orientations toward an arm or entries in the proximal portion of an arm [Brown, M.F., 1992. Does a cognitive map guide choices in the radial arm maze? J. Exp. Psychol., Anim. Behav. Processes 18, 56-66]. These measures were used as indexes of performance, within-trial retroactive intrusion, memory trace decay and choice behavior, respectively. As generally observed in the literature, the frequency of errors was higher in rats of the FX group than in rats of the SH group; the impairment persisted even after the training criterion was reached. The analysis of latency to arm re-entry and of the number of choices separating re-entries suggested that this impairment was the result of faster memory decay rather than retroactive interference. Both FX and SH groups exhibited a systematic pattern of microchoices, but the frequency of microchoices was higher in FX lesioned rats than in SH controls. Moreover, in lesioned animals, relatively fewer of the initial microchoices were directed toward the baited arms during training-to-criterion. Some of the results provide support to the working memory theory [Olton, D.S., Becker, J.T., Handelmann, G.E., 1979. Hippocampus, space, and memory. Behav. Brain Sci. 2, 313-365], whereas others look more consistent with the cognitive map view [O'Keefe, J., Nadel, L., 1978. The Hippocampus as a Cognitive Map. Clarendon Press, Oxford]. The discussion suggests that both theories and a distinction between prospective and retrospective memory may be required to account for the function of the hippocampal formation in memory.

Animals↗

An analysis of adult social spacing tendencies and related social interactions in a colony of spider monkeys (Ateles geoffroyi) at the San Francisco zoo.

Observations on adult interindividual spacing and social interactions for 13 spider monkeys (Ateles geoffroyi) of an approximately 48 animal captive colony were made from mid-June through August 1972. In this analysis the interanimal distances, general activities, and social interactions per minute observation for each subject were compared for a sample of 7 sexually mature males and 6 sexually mature females. Association tendencies between members of the same sex were significantly high as were exchanges of the taxon-specific 'pectoral sniff and embrane" interactions and grooming. The direction and nature of agonistic interactions was predominantly intersexual and involved frequent attacks by single or multiple males against females. Comparisons with a feral population of spider monkeys (Ateles belzebuth) revealed marked similarities in spatial affinities and patterns of social interaction.

Agonistic Behavior↗

Neural correlates of individual differences in spatial learning strategies.

Behavioral studies have shown that spatial skills, such as mental rotation, are correlated with preferences for certain types of spatial information. To be more specific, better mental rotation is associated with a preference for survey (maplike) spatial information relative to route (landmark or wayfinding) information. Functional MRI was used to investigate how individual differences in spatial skills (mental rotation) interact with encoding information from these 2 spatial perspectives. Despite similarities in performance across individuals for route and survey learning, differences between route and survey encoding activation increased with increased mental rotation ability in anterior cingulate, middle frontal gyrus, and postcentral gyrus. This correlation appeared to be due to decreasing activation during survey encoding and not activation changes during route learning. The results suggest that mental rotation skill contributes to survey or map learning but that alternative strategies can be used under the circumstances of this study to achieve equal performance.

Adult↗

Temperament, social competence, and adrenocortical activity in preschoolers.

The relations among temperament, social competence, and levels of a stress-sensitive hormone (salivary cortisol) were examined in two studies of preschoolers children (Study 1, N = 29; Study 2, N = 46). In both studies, we sampled cortisol daily for the initial weeks of school year (Group Formation period) and for several weeks later in the year (Familiar Group period). For each child, we examined two measures of cortisol activity (separately for each period) based on the distribution of cortisol levels across days: (a) median cortisol (50th percentile) and (b) cortisol reactivity (the difference between the 75th and 50th percentile). Median cortisol was modestly stable across periods, but cortisol reactivity was not. Children who showed high cortisol reactivity (75th minus 50th percentile > or = 0.10 micrograms/dl) during the Group Formation period but low-to-normal cortisol reactivity during the Familiar Group period were outgoing, competent, and well liked by their peers. In contrast, children who changed from low/normal to high cortisol reactivity and those who maintained high cortisol reactivity from the Group Formation to Familiar Group period were affectively negative and solitary. Children who showed high median cortisol during the Familiar Group period or over both periods scored lower on a measure of attentional and inhibitory control. Together, these results suggest that relations among temperament, social competence, and neuroendocrine reactivity reflect both individual and contextual differences.

Affect↗

Nongenomic inheritance of emotional reactivity in Japanese quail.

Avian scientific literature includes few reports on the influence of characteristics of mothers on the behavior of their offspring. By comparing young domestic Japanese quail raised by adoptive mothers with high levels of general emotional reactivity (E+ mothers) to young raised by adoptive mothers with low levels of general emotional reactivity (E- mothers), we evaluated the influence of characteristics of mothers on the behavioral development of their offspring. Our results revealed that general emotional reactivity was higher in young raised by E+ mothers than in young raised by E- mothers. These differences were significant in the presence of mothers as well as after separation from them, suggesting direct as well as long-term maternal influence. Young raised by E+ mothers also presented delayed increases in weight.

Animals↗

Behavioral specializations of SI and SII cortex: a comparative examination of the neural logic of touch in rats, cats, and other mammals.

In what ways do passive touch and active touch require particular properties of cortical physiology? Because it is not easy to make predictions "bottom up" from neurophysiology and anatomy to behavior, there have been surprises in studying behavioral deficits following selective ablations of SI versus SII. For example, in earlier research on cats, unilateral ablation of SI unexpectedly had no effect on passive touch but did cause contralateral losses in posture and movement; it was ablation of SII plus subjacent cortex that led to contralateral losses in passive touch. In contrast, in a recent experiment with rats unilateral ablation of either SI or SII caused contralateral losses both in touch and postural reflexes. Some of the literature on dogs, monkeys, and humans suggests similarities with cats. To better understand these comparative findings, the following theoretical factors are considered: the degree of diffuseness versus specificity in brain input-output relations demanded or permitted by a behavior, the spatial and temporal scales of a behavior, the species' degree of encephalization, the need for stimulus generalization or functional equivalence of movements, and the relative sizes and sensitivities of different parts of the body. Hypotheses are also offered about why the evolution in rats of shortened forelimbs and increased vibrissal function may have entailed a peculiar compromise between active and passive touch and between functions of SI and SII.

Animals↗

Task force report: sociophysical settings and mental health: opportunities for mental health services planning.

President Kennedy's "bold new approach" remains compelling 15 years after it was first announced. Mental health services at the community level have come a long way since the community mental health center program's establishment in 1963. Mental health manpower, advances in treatment technology, and volumes of service all have grown remarkably; but much still remains to be done to integrate community mental health services into the communities they serve in the planning of human services generally, and particularly in emphasis on preventive care. The National Council of Community Mental Health Centers Environmental Assessment Task Force has two closely related charges in these latter areas. First, to inquire into the "environmental" aspects of mental health at the community level; and, second, to explore environmental perspectives for the establishment of prevention initiatives in the delivery of services. This paper explores that charge by seeking a perspective on environment that traces the intersection of the built environment and social-interpersonal behavior with special attention to the implications for mental well-being. Implications of this perspective for community mental health center roles in community planning are considered, with reference to the establishment of preventive services.

Community Mental Health Centers↗

Agonistic display and spacing in the black-headed gull, Larus ridibundus.

Black-headed gulls nesting on islands in a marsh habitat had a higher breeding success than those nesting on the periphery of the colony. Island birds maintained close inter-nest distances whereas peripheral nests were spaced further apart as predation of eggs increased. These changes in spacing corresponded with changes in the response distances of agonistic displays. There was no change during incubation for island birds but peripheral birds displayed to intruders at much greater distances than during pair formation. Island birds were more likely to attack and display more frequently to intruders than peripheral birds. However, in one season the peripheral birds were more aggressive during pair formation because of an increase in intrusions by unpaired females.

Aggression↗

Face and politeness in pharmacist-physician interaction.

This study used Brown and Levinson's theory of politeness to gain a better understanding of the factors that influence pharmacists' messages to physicians. Specifically, perceived differences in power and social distance between pharmacist and physician were expected to influence the amount of politeness observed in pharmacists' messages. The effects of age, sex and practice context were also examined. Written messages were gathered from 210 community pharmacists and 112 hospital pharmacists in response to a hypothetical drug allergy scenario. Messages were segmented into independent clauses, and independent clauses were classified according to the politeness strategy used to make allergy reports and alternative drug recommendations respectively. Content analysis of the messages in relation to demographic variables revealed that age and practice context were significantly associated with the overall level of politeness of alternative drug recommendations, but not with overall politeness of allergy reports. Demographic factors were significantly related to perceptions of power and social distance, but, contrary to Brown and Levinson's prediction, these perceptions were not associated with variation in politeness. Regardless of other factors, recommendations were made more politely than reports. Implications for pharmacists' professional roles and identities are discussed.

Adult↗

Why do dolphins jump? Interpreting the behavioural repertoire of bottlenose dolphins (Tursiops sp.) in Doubtful Sound, New Zealand.

Only a limited number of studies have tried to determine the purpose of surface behavioural events performed by dolphins. To date only one study has attempted to aggregate the behavioural events observed in a population in contextual groups using co-occurrence as the grouping factor. In the present study, I tried to characterise the behavioural repertoire of a bottlenose dolphin population (Tursiops sp.) present in Doubtful Sound, New Zealand. I first looked at the relationship between events performed by individuals depending on the behavioural state of their schools. I then assessed the likelihood for events to co-occur. Four main behavioural categories (orientation, travel, social displays and fights) emerged from this analysis. Aerial events (jumps) did not fall into one category, showing that different aerial behaviours play different roles. Moreover, it appears that dolphins used side-flopping and upside-down lobtailing to communicate motivation. Side-flops occurred when the focal schools finished a behavioural bout and started to travel, while upside-down lobtails occurred when the focal schools instigated a behavioural bout after travelling. This non-vocal communication can take place over a few meters to hundreds of meters. Having signals that are effective over very short ranges avoids unwanted signalling to prey, predators or conspecifics.

Animal Communication↗

Idiosyncratic route-based memories in desert ants, Melophorus bagoti: how do they interact with path-integration vectors?

Individually foraging desert ants of central Australia, Melophorus bagoti, exhibit amazingly precise mechanisms of visual landmark guidance when navigating through cluttered environments. If trained to shuttle back and forth between the nest and a feeder, they establish habitual outbound and inbound routes, which guide them idiosyncratically across the natural maze of extended arrays of grass tussocks covering their foraging areas. The route-based memories that usually differ between outbound and inbound runs are acquired already during the first runs to the nest and feeder. If the ants are displaced sideways of their habitual routes, they can enter their stereotyped routes at any place and then follow these routes with the same accuracy as if they had started at the usual point of departure. Furthermore, the accuracy of maintaining a route does not depend on whether homebound ants have been captured at the feeder shortly before starting their home run and, hence, with their home vector still fully available (full-vector ants), or whether they have been captured at the nest after they had already completed their home run (zero-vector ants). Hence, individual landmark memories can be retrieved independently of the state of the path-integration vector with which they have been associated during the acquisition phase of learning. However, the ants display their path-integration vector when displaced from the feeder to unfamiliar territory.

Animals↗